Field of the Invention
The present invention relates to methods and compositions, particularly for treatment of attention deficit disorder.
Description of the Prior Art
Sustained release dosage forms are important in the search for improved therapy, both through improved patient compliance and decreased incidences of adverse drug reactions.
It is the intent of sustained release formulations to provide a longer period of pharmacologic action after administration than is ordinarily obtained after administration of immediate release dosage forms. Sustained release compositions may be used to delay absorption of a medicament until it has reached certain portions of the alimentary tract, and maintain a desired concentration of the medicament in the blood stream for a longer duration than would occur if conventional rapid release dosage forms arc administered. Such longer periods of response provide for many therapeutic benefits that are not achieved with corresponding short acting, immediate release preparations. Thus, therapy may be continued without interrupting the sleep of the patient, which is of special importance, for example, when treating a patient for moderate to severe pain (e.g., a post-surgery patient, a cancer patient, etc.), or for those patients who experience migraine headaches on awakening, as well us for the debilitated patient for whom sleep is essential. A further general advantage of longer acting drug preparations is improved patient compliance resulting from the avoidance of missed doses through patient forgetfulness.
Unless conventional rapid acting drug therapy is carefully administered at frequent intervals to maintain effective steady state blood levels of the drug, peaks and valleys in the blood level of the active drug occur due to rapid absorption, systemic excretion of the compound and through metabolic inactivation, thereby producing special problems in maintenance therapy of the patient.
In view of this, it is considered a goal of many skilled in the art that a controlled release dosage form will ideally provide therapeutic concentration of the drug in blood that is maintained throughout the dosing interval with a reduction in the peak/trough concentration ratio. Central to the development process arc the many variables that influence the in vivo release and subsequent absorption of the active ingredients from the gastrointestinal tract.
It is known in the pharmaceutical art to prepare compositions which provide for sustained release of pharmacologically active substances contained in the compositions after oral administration to humans and animals. Sustained release formulations known in the art include specially coated pellets, coated tablets and capsules, and ion exchange resins, wherein the slow release of the active medicament is brought about through selective breakdown of the coating of the preparation or through compounding with a special matrix to affect the release of a drug. Some sustained release formulations provide for related sequential release of a single close of an active compound at predetermined periods after administration.
Thus, sustained release dosage forms arc important in the search for improved therapy, both through improved patient compliance and decreased incidences of adverse drug reactions.
While controlled and/or sustained release compositions have constituted a definite advance in the art, improvements in these compositions have been sought, particularly for preparations available for conditions such as Attention Deficit Hyperactivity Disorder (ADHD), diabetes etc.
Attention Deficit Disorders arc the most common psychiatric disorders in children (Campbell et al. 1992) with reported rates ranging from 4% to 9% (Aman et al. 1983).
Attention Deficit Disorder (ADD) is characterized by inattention and impulstvity and may be present with hyperactivity (ADHD) (Shaywitz et al. 1984). Other characteristics may include aggressiveness, stealing, lying, truancy, setting fires, running away, explosiveness, cognitive and learning problems as well as poor social skills (Campbell et al. 1992). It is four to five times more frequent in boys than girls (Campbell et al. 1992).
Stimulant medication, such as amphetamines, have been shown to be the most effective agents in the treatment of children with disorders of activity modulation and attention regulation and result in significant improvement in 70 to 80 per cent of affected children (Shaywitz et al. 1984). Positive effects of stimulants have been documented in a variety of areas including behavioral, social, perceptual performance, motor activity, impulse control, attention regulation and cognitive performance (Barkley 1977, Kavale 1983, Offenbacher et al. 1983. Rosenthalet al 1978).
Long thought of as a childhood disorder, ADHD is now known to persist into adolescence and adulthood (Practice Parameter for the Use of Stimulant Medications in the treatment of Children. Adolescents, and Adults. J. AM. ACAD. CHILD ADOLESC. PSYCHIATRY. 41:2 SUPPLEMENT, FEBRUARY 2002)
Methylphenidate [dl-threo-methyl-2-phenyl-2-(2-piperidyl)acetate] is the psycho-stimulant used most frequently in the treatment of hyperactivity and attention deficit disorder. It appears to have a higher incidence of positive effects and a lower incidence of adverse effects than other psychostimulants. The efficacy of methylphenidate (“MPH”) in improving attention and behavioral symptoms has been supported by many studies.
Immediate release methylphenidate preparations, because of their short half-life, require frequent administration at short intervals to ensure adequate treatment throughout a child's school day, adolescence's school day (high school, college, university) and adult working day. The rapid onset and offset of immediate release methylphenidate preparations means that a medicated person with attention deficit disorder all be maximally affected only for relatively brief periods during the day. Due to its short half-life, it been known to administer MPH given twice per day, usually once after breakfast and once during the day, an event that some children and some school personnel apparently avoid, resulting in poor compliance with prescribed regimens (Brown et al, 1985Firestone 1982),
Compliance is a major problem or children, adolescences and adults. Poor compliance in taking medication may explain, in part, variable and conflicting results reported in many studies of the effect of medication on improving the behavior of hyperactive children, adolescents and adults. These limitations of immediate release methylphenidate led to interest in products with longer effective periods of action.
Thus, much of the prior art has focused on development of formulations for treatment of ADHD with a focus on administration to children and improving patient compliance in the patient population. This has led to commercialization of a number of sustained release formulations of methylphenidate—e.g., Ritalin SR™, Concerta™ and Biphentin™.
Duration of efficacy with long-acting methylphenidate formulations was maintained from one hour to 12 hours post-dosing for osmotically controlled-release oral delivery systems (four trials), 1.5 hours to 7.5 hours for methylphenidate extended release in one trial, one hour to 12 hours post-dosing for methylphenidate spheroidal oral drug absorption systems (two trials) and 30 minutes to 12 hours post-dosing for dexmethylphenidate extended release (five trials). Most long-acting stimulants conferred benefits on ADHD symptoms in patients across the age spectrum to 12 hours after a single morning dose as measured by the permanent product measure of performance mathematics test (PERMP). Formulations may differ in time to peak effect and maintenance of effect as well as magnitude of effect at different tune points during the day (Brams M, Moon E, Pucci M, Lopez F A. Duration of effect of oral long-acting stimulant medications for ADHD throughout the day. Curr Med Res Opin. 2010 August, 26(8):1809-25 doi: 10.1185/03007995.2010.488553).
Despite the advances in the art, there is still room for improvement.
First, some or all of the commercially available sustained release formulations of methylphenidate do not have, in combination, a rapid onset of action and a duration of action that exceeds 12 hours. The provision of a sustained release formulation having this combination of features would be highly desirable for adolescents or adults whose daily activities require them to have a rapid onset of therapeutic effect and duration of action that lasts at least 14 hours to get them through the days and will into the evening without the need of another dose of the medication.
Second, some or all of the commercially available sustained release formulations of methylphenidate are susceptible to premature release of the active ingredient in a gastric environment that contains alcohol (e.g., ethanol). This can be a significant problem if the subject taking the formulation is an alcohol abuser.
This, it would be highly desirable to have a pharmaceutical composition that obviates or mitigates one or both of these problems in the prior art.